Photographic emulsion layer containing a derivative of a hydroxyalkyl ether of a polyhydric alcohol



Patented Apr. 29, 1941 rnorocaarurc EMULSION LAYER coN- TAINING A DERIVATIVE OF A HYDROXY- ALKYL ETHER OF A POLYHYDRIO ALCO- nor.

DonaldR. Swan and Carl G. Lindquist, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application March 2, 1940, Serial No. 321,900

Claims.

This invention relates tophotographic lightsensitive materials, such as sensitized film, plates, and paper, comprising layers in which sensitive silver salts are suspended or dispersed in gelatin or other suitable vehicle, and optionally com-' containing such a spreading agent. The gen-' eral process of coating film base with a sensitive gelatin emulsion layer, setting by chilling, and overcoatlng with a protective gelatin layer, is fully set forth in U. 8. Patent No. 1,699,349 of William B. Dailey.

If a sensitive gelatlno-sllver-halide emulsion is coated on a film base (which has usually first been coated with a thin layer or sub-stratum of gelatin or other colloid and dried) without the addition of a suitable spreading agent, difllculty is experienced in that the emulsion will spread unevenly. Moreover, if the emulsion, while still in a wet, chilled condition, is overcoated with a protective gelatin coating, air bubbles form between the emulsion layer and the protective layer. Either of these defects, of course, greatly impairs the quality of the photographic film.

It has, therefore, been customary in the art to add certain agents, such, for instance, as saponin, to the sensitive emulsion in order to avoid these defects as far as possible. Saponin has surfaceactive properties, and not only acts as a spreading agent for gelatin, but by some mechanism not clearly understood, it prevents the formation of air bubbles between the gelatin layers when a wet, chilled gelatin emulsion layer containing the proper concentration of saponin is overcoated with a warm gelatin solution.

However, saponin, being a naturally occurring tion or other hydrophilic colloid of the type which ment in spreading. This is true whether the saponin be employed in the emulsion layer or in the protective overcoating or other layer.

Other surface-active materials have been tried in place of saponin, but many of them, while they may act to some extent as spreading agents for gelatin, have been found to be entirely ineffective for preventing the formation of air bubbles when a wet, chilled gelatin emulsion containing them is overcoated with a warm gelatin solution, and many of them are objectionable from the standpoint of fogging or desensitizing the emulsion.

We have found a class of surface-active compounds which are not only excellent spreading agents for gelatin and other hydrophilic colloid layers which are deposited from a predominantly aqueous medium and used in photographic films, plates, and paper, but which, when incorporated in layers such as sensitive gelatin emulsions, are superior to saponin in the prevention of bubble formation when the wet, chilled emulsion layer is overcoated with a warm gelatin soluis deposited from a predominantly aqueous medium. These compounds are the alkylene glycol ethers of polyhydric alcohols of at least 3 hydroxyl groups, in which at least one of the.

alkvlene glycol radicals iscompounded with a radical selected from the group consisting of the aliphatic alkyl and acyl radicals of from 8 to 18 carbon atoms and the alicyclic alkyl and acyl radicals, the compound being water-soluble. In other words; at least one of the alkylene glycol radicals is etherified or ester-ified with an aliphatic radical containing from 8' to 18 carbon atoms or with an alicyclic radical. The preparation of these compounds is described in U. S. Patents 1,959,930 and 2,069,336 of Otto Schmidt and Egon Meyer. The compounds useful in carrying out our invention may be represented by the formula (O alkylene0R)n R v (Oalkylene-0H),. in which R is the hydrocarbon radical of a polyhydric alcohol of at least 3 hydroxyl groups material of vegetable origin, is of varying quality,

and synthetic agents are to be preferred because of their more constant and controlled properties.

(that is, R represents the polyhydric alcohol minus its hydroxyl groups) n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is selected from the group consisting of, the aliphatic alkyl and acyl radicals of from 8 to 18 carbon atoms and the alicyclic alkyl and acyl radicals. Of the aliphatic radicals,

.to 2% in the dried emulsion layer.

' tol, sorbitol, mannitol, etc.

These polyhydric alcohol derivatives may be incorporated in the sensitive gelatin emulsion at any point in its manufacture such that they will be present during its coating, in the proportion of from 0.002 to 0.2 part of the derivative per 100 parts by weight of wet emulsion. This gives a polyhydric alcohol derivative content of 0.02% They have no detrimental effect on the photographic properties of the emulsion, but, on the contrary, improve them. For example, they improve the aging qualities of the emulsion. Photographic. films in which the sensitive emulsion contains the above-' mentioned proportions of the polyhydric alcohol derivatives defined have been found to show higher speed and less fog after prolonged storage at elevated temperatures than ordinary film, stored for the same length of time under the same conditions. They are also more readily wet by the developing solution.

It is believed that the property of the spreading agent which prevents the formation of air bubbles when a wet, chilled gelatin emulsion is overcoated with a warm gelatin solution, also tends to prevent the formation of air bubbles, repellent spots, etc., on the surface .of a sensitive emulsion containing such a spreading agent, when that emulsion, coated on a film, plate, paper, etc., is immersed in a developer.

As above pointed out, the polyhydric alcohol derivatives defined may be used in any one or more of the colloid layers used to build up a photographic sensitive element .upon a base such as film, glass, paper, etc., which layers consist of gelatin or other hydrophilic colloid which is deposited from a predominantly aqueous medium, i. e., a medium used as the solvent for such materials in which water predominates, the remainder of the medium contributing to give a good dispersion of the colloid. If two superposed colloid layers are present, either, neither or both of which may be. photographically sensitive, the spreading'agent may be used in either layer or in both layers. However, where a wet, chilled lightsensitive gelatin or similar layer is to be overcoated with a warm solution or emulsion. of gelatin or similar material, the presence of the spreading agent in the wet, chilled layer is essential for preventing the formation of air bubbles between the layers. Examples of such hydrophilic colloids other than gelatin, which are useful as layers in photographic films, plates, paper, etc., are the water-soluble cellulose derivatives such as well hydrolyzed cellulose acetate (described in U. S. Patent No. 2,110,491 of Salo) and cellulose esters of hydroxy monocarboxylic acids, such as lactic or glycollic, and salts of cellulose esters of dicarboxylic acids, such as phthalic (described in U. S. Patent 'No. 2,127,573 of Sheppard and U. S. Patent No. 2,127,621 of Staud), as well as polyvinyl alcohol and hydrolyzed polyvinyl acetate (described in applications of Wesley G. Lowe, Serial Nos. 318,559 and 318,560, filed February 12, 1940) and water-soluble polyvinyl acetals (described in an application of Charles R. Fordyce, Serial No. 221,584, filed July 2'1, 1938, Patent No. 2,211,323). When colloids other than gelatin are used, it may be desirable to coat them at diflerent temperatures.

In the claims appended hereto, where a hydrophilic colloid depositable from a predominantly aqueous medium is referred to, it will be understood to mean any hydrophilic colloid which can be deposited from a medium which is pre dominantly aqueous, the remainder of the medium being an organic solvent which contributes to the dispersibility of the colloid; examples of such organic solvents for this purpose are acetone, ethyl alcohol, ethylene glycol, monoacetin and pyridine.

What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. Photographic sensitive material comprising a layer of a hydrophilic colloid depositable from a predominantly aqueous medium, said layer containing from 0.02% to 2% of a water-soluble compound having the formula in which R is the hydrocarbon radical of a poly-- hydric alcohol of at least 3 hydroxyl groups, n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is selected from the group consisting of the aliphatic alkyl and acyl radicals of from 8 to 18 carbon atoms and the alicyclic alkyl and acyl radicals.

2. Photographic sensitive material comprising a base, a photo-sensitive gelatin emulsion layer and a gelatin overcoating on the emulsion, in which the photo-sensitive gelatin emulsion layer contains from 0.02% to 2% of a water-soluble compound having the formula in which R is the hydrocarbon radical of a polyhydric alcohol of at least 3 hydroxyl groups, n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is selected from the group consisting of the aliphatic alkyl and acyl radicals of from 8 to 18 carbon atoms and the alicyclic alkyl and acyl radicals.

3. Photographic sensitive material comprising a base, a photo-sensitive gelatin emulsion layer and a gelatin overcoating on the emulsion, in which. the photo-sensitive gelatin emulsion layer contains from 0.02% to 2% of a compound having the formula in which R is the hydrocarbon radical of a polyhydric alcohol of at least 3 hydroxyl groups, n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is lauroyl.

4. Photographic sensitive material comprising a base, a photo-sensitive gelatin emulsion layer and a gelatin pvercoatlng on the emulsion, in which the photo-sensitive gelatin emulsion layer RI (Oa1ky1eneOH),, in which R is the hydrocarbon radical of a polyhydric alcohol of at least 3 hydroxyl groups. n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is naphthenoyl.

5. Photographic sensitive material comprising a base, a photo-sensitive gelatin emulsion layer and a gelatin overcoating on the emulsion, in

which the photo-sensitive gelatin emulsion layer contains from 0.02% to 2% of a compound having the formula (O-alkylene- R) R\ (O-alky1ene-OH), in which R is the hydrocarbon radical of a polyhydric alcohol of at least-3 hydroxyl groups, n and p are positive integers whose sum equals the number of hydroxyl groups originally present in the polyhydric alcohol, and R is abietoyl.

' DONALD R. SWAN.

CARL G. LINDQUIST. 

